Backed ply material and apparatus for forming same

ABSTRACT

A layered material may include a ply material and a backing film disposed upon the ply material. The backing film may comprise a polyester film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a divisional of U.S.application Ser. No. 11/528,353 entitled BACKING FILM FOR PLY MATERIALS,filed on Sep. 28, 2006, the entire contents of which is expresslyincorporated by reference in its entirety herein.

FIELD

The present disclosure generally relates to backing materials for sheetand roll stock. More particularly, the present disclosure pertains to animproved backing material for pre-impregnated ply material.

BACKGROUND

Composite structures are typically constructed from multiple layers orplies. These plies may include a variety of materials such as carbonfiber, various other fibers, metal foils, and the like. In addition, theplies may be pre-impregnated with a resin and are often dispensed from aroll or spool. In roll form, the ply material is referred to as “tape”and typically includes a paper backing film. This backing film generallyprevents pre-impregnated ply material (prepreg) from adhering to itselfand aids in handling the ply as the ply is applied to the tool and thelayup. In particular, at the beginning and end of each ply placement,the ply material is generally cut to match the profile of the layupwhile the backing film is left intact. In this manner, the intactbacking film is utilized to guide the severed ply on to the layup.During the layup process, the backing film is removed prior to placementof any subsequent ply.

A disadvantage associated with conventional backing film material isthat the backing film rips or tears. In particular, cuts in the backingfilm, introduced during the ply cutting procedure, often serve as astarting point for a tear. As the backing film is removed, torn backingfilm may remain on the ply, may foul the ply placement head, and/or maylead to breakage of the backing film.

Another disadvantage associated with conventional backing film is thatit is usually a relatively thick calendared claycote type paper. Theweight and thickness of this paper reduce the yardage of ply materialthat may be placed on a spool of a given diameter. Reducing thethickness of the conventional backing film in an effort to place morebacked ply material on a spool, however, increases the tendency of thebacking film to tear.

Yet another disadvantage associated with conventional backings films isthe opaque nature of the paper. This opacity precludes visual inspectionof the ply placement until the backing film is removed. Once the backingfilm is removed from the ply, the handling characteristics of the plyare negatively impacted so, it is difficult or impossible to adjust theply placement

Accordingly, it is desirable to provide a backing film forpre-impregnated ply material that is capable of overcoming thedisadvantages described herein at least to some extent.

BRIEF SUMMARY

The foregoing needs are met, to a great extent, by the presentdisclosure, wherein in some embodiments an improved backing film forpre-impregnated ply material is provided.

An embodiment of the present disclosure relates to a layered material.The layered material includes a ply material and a backing film disposedupon the ply material. The backing film includes a polyester film.

Another embodiment of the present disclosure pertains to an apparatusfor generating backed ply material. The apparatus includes a means fordisposing a polyester film upon a ply material and a means forgenerating a roll of the backed ply material by wrapping the backed plymaterial about a spool.

Yet another embodiment of the present disclosure relates to an apparatusfor generating a composite layup. The apparatus includes a means fortacking a ply material having a polyester backing film to a tool. Theapparatus further includes a means for disposing the ply material uponthe tool along a path and a means for removing the polyester backingfilm.

Yet another embodiment of the present disclosure pertains to a method ofgenerating a backed ply material. In this method, a polyester film isdisposed upon a ply material.

Yet another embodiment of the present disclosure relates to a method ofgenerating a composite layup. In this method, a ply material having apolyester backing film is tacked to a tool, the ply material is disposedupon the tool along a path, and the polyester backing film is removed.

There has thus been outlined, rather broadly, certain embodiments of thedisclosure in order that the detailed description thereof herein may bebetter understood, and in order that the present contribution to the artmay be better appreciated. There are, of course, additional embodimentsof the disclosure that will be described below and which will form thesubject matter of the claims appended hereto.

In this respect, before explaining at least one embodiment of thedisclosure in detail, it is to be understood that the disclosure is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The disclosure is capable of embodiments inaddition to those described and of being practiced and carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract, are for thepurpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conceptionupon which this disclosure is based may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present disclosure. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is perspective view of ply material according to an embodiment ofthe disclosure.

FIG. 2 is a simplified side view of a tape laying head suitable for usewith the ply material according to FIG. 1.

FIG. 3 is a perspective view of a contour tape lamination machinesuitable for use with the ply material according to FIG. 1.

FIG. 4 is a flow diagram of a method of placing plies to produce acomposite structure or product according to an embodiment of thedisclosure.

FIG. 5 is a flow diagram of a method to generate a backed ply materialaccording to FIG. 1.

DETAILED DESCRIPTION

The present disclosure provides, in some embodiments, a backingmaterial, a backed composite ply material, and a method of generating abacked ply material. An embodiment of the disclosure will now bedescribed with reference to the drawing figures, in which like referencenumerals refer to like parts throughout. As shown in FIG. 1, a backedply material 10 includes a ply material 12 and a backing 14. In variousembodiments of the disclosure, the ply material 12 may include anysuitable sheet stock. Examples of suitable sheet stocks include: wovenfiber fabric; oriented strand tape; metal foil such as aluminum alloyand titanium foil; composite materials such as titanium graphitecomposites; and the like. In a particular embodiment, the ply material12 is a graphite fiber tape pre-impregnated with an epoxy resin(pre-preg). In another particular embodiment, the ply material 12 is anepoxy resin coated titanium foil.

In general, the backing 14 lends support to the ply material 12 and aidsin handling the ply material 12. As described herein, the backed plymaterial 10 is typically rolled on to a spool in preparation fordispensing. For a given thickness of the ply material 12 rolled into agiven diameter spool, the thickness of the backing 14 has an inverselyproportional relationship with the length of ply material 12 that may beplaced on the spool. That is, the thinner the backing 14, the more plymaterial 12 will fit onto the spool. Longer lengths of ply material 12are generally preferred due to the decreased number of splices that mustbe prepared, reduced downtime as a result of the decreased number ofsplices, and reduced number of spool change operation to be performed.Thus, it is preferable that the backing 12 is thin. In addition, thethickness of this backing 14 is varied depending upon the particularapplication. For example, according to various embodiments of thedisclosure, for typical composite layup applications, the thickness ofthe backing 14 is from about 0.001 inches (1 mil) to about 0.004 inches(4 mil). More preferably, the thickness of the backing 14 is about 1 milto about 2 mil. However, in other embodiments, the thickness of thebacking 14 is less than 1 mil. For example, when constructing relativelysmall and/or convoluted items such as, hand held or smaller devices, itmay be advantageous that the ply material 12 be approximately 1 milthick or less and the backing 14 be approximately 0.1 mil thick or less.In yet other embodiments, the thickness of the backing 14 is greaterthan 4 mil. For example, when constructing items with relatively thick(3 millimeters or more) or otherwise difficult to handle ply material12, the backing 14 may be 10 or more mil thick.

During layup operations, the backing 14 is typically removed. To reducedown time, it is also preferable that the backing 14 is tear-resistant.For example, the backing 14 may include a polymeric or otherwise toughresilient material. According to an embodiment of the disclosure, thebacking 14 includes a suitable polyester film. Suitable polyester filmsinclude at least polyethylene terephthalate (PET) and heat stabilizedPET. In this regard, when applying heat during layup operations, it maybe advantageous to utilize a heat stabilized PET. To further facilitateremoval of the backing 14 from the ply material 12, the backing 14optionally includes a suitable release agent. Suitable release agentsinclude at least silicone release agents applied by Tribex Corp. ofRocklin Calif., USA. Optionally, the backing 14 is substantiallytransparent to facilitate inspection of seams between abutting plies.For example, a 2 mil film of PET is essentially transparent.

FIG. 2 is a simplified side view of a tape laying head 18 suitable foruse with the backed ply material 10 according to FIG. 1. As shown inFIG. 2, the tape laying head 18 includes a supply spool 20, take-up reel22, a shoe or compaction roller 24, cutting assembly 26, heater assembly28, material feeder 30, and guide chute 32. The tape laying head 18dispenses the ply material 12 upon a tool 34 as it moves in direction Arelative to the tool 34. More particularly, the supply spool 20 and thetake-up reel 22 rotate in the respectively indicated directions to causebacked ply material 10 to advance through the tape laying head 18 asindicated. The supply spool 20 and/or the take-up reel 22 are optionallycontrolled to rotate via the action of, for example, one or more servoaxis motors. Following application of the ply material 12 upon the tool34, the backing 14 is removed and collected by, for example, the take-upreel 22. However, the take-up reel 22 is optional and thus, the backing14 may be removed in any suitable manner such as, for example, manually,a backing removal device, or the like. Depending upon the particularapplication, the placement of the ply material 12 may be inspected priorto removal of the backing 14. In this regard, it is an advantage of someembodiments of the disclosure that the backing 14 is substantiallytransparent and thus, the placement of the ply material 14 may beplainly visible through the backing 14.

The cutting assembly 26 may employ any known cutting device such asvarious bladed devices, abrasive cutters, high pressure jets, lasers,and the like. In a specific example, the cutting assembly 26 includes anultrasonic knife that is caused to vibrate by an ultrasonic transducerand controlled to rotate by the action of a motor. The ultrasonic knifeis further controlled to traverse the full width of the backed plymaterial 10 or any portion thereof by the action of a motor configuredto rotate a jackscrew. Furthermore, the cutting assembly 26 may employmore than one cutting device. For example, the cutting assembly 26 of anembodiment of the disclosure includes two cutting devices controlled toperform cutting operations in a substantially simultaneous manner.

When utilizing specific materials and/or operating conditions in whichheating of the material is advantageous, the heater assembly 28 isconfigured to impart thermal energy upon the backed ply material 10. Inthis regard, any known device operable to heat the backed ply material10 in a suitable manner may be utilized by various embodiments of thedisclosure. For example, the heater assembly 28 may include a divertervalve configured to control the flow of heated air directed onto thebacked ply material 10. In addition, to the heater assembly 28, the tapelaying head 18 may include various supplemental heaters such as, forexample, a guide chute heater, a heater following the compactions roller24, and the like.

FIG. 3 is a perspective view of a contour tape lamination machine (CTLM)38 suitable for use with the backed ply material 10 according to FIG. 1.As shown in FIG. 3, the CTLM 38 is of a gantry-type and, as such,includes a gantry 40, the tape laying head 18, and the tool 34. Thegantry 40 is configured to control the movement of the tape laying head18 in relation to the tool 34 and the ply material 12 laid upon the tool34. In an embodiment of the disclosure, the gantry 40 is configured tocontrol ten axis of movement (five axis of the gantry and five axis ofthe tape laying head 18). However, it is to be understood that thespecific number of axis may depend upon the particular operatingcondition and thus, the number of axis controlled is not critical to thedisclosure.

FIG. 4 illustrates steps involved in a method 44 of placing plies toproduce a composite structure or product. Prior to the initiation of themethod 44, a composite product is designed and a series of computerreadable instructions specifying attributes of the composite product isgenerated. These instructions are utilized to control the operations ofthe CTLM 38 and construct a form such as the tool 34. This form isfurther positioned within the operational area of the CTLM 38.

At step 46, the method 44 is initiated by turning on the variouscomponents of the CTLM 38 described herein above and executing thecomputer readable instructions.

At step 48, the backed ply material 10 is advanced to an initial point.For example, the take up reel 22 and/or the supply spool 20 may becontrolled to advance the backing 14 through the tape laying head 18until an end of the ply material 12 is positioned between the compactionroller 24 and the tool 34. In another example, the rollers of thematerial feeder 30 may engage the backed ply material 10 and advance theply through the tape laying head 18 until the backed ply material 10 ispositioned to be applied to the tool 34, referred to as being tacked. Toensure the backed ply material 10 has advanced a suitable amount, asensor and/or operator may sense the position of the backed ply material10. In addition, the location on the tool 34 is determined based uponthe series of computer readable instruction and/or the location of apreviously positioned ply material 12. Furthermore, prior to tacking theply material 12 to the substrate at step 50, the end of the ply material12 is, optionally, cut based upon the series of computer readableinstruction, the orientation of a previously positioned ply material 12,and/or the location of a previously positioned ply material 12. In aparticular example, cutting of the ply material 12 may be performed at acontrolled depth of cut so as to substantially sever the ply material 12while leaving the backing 14 substantially uncut.

At step 50, the backed ply material 10 is tacked to the substrate. In anembodiment of the disclosure, the backed ply material 10 is tacked bypositioning the tape laying head 18 with the CTLM 38 such that thecompaction roller 24 or a shoe is controlled to press the backed plymaterial 10 on to the substrate with sufficient force so as to cause thebacked ply material 10 to adhere to the substrate.

At step 52, the backed ply material 10 is dispensed along a path acrossthe tool 34. In order to minimize deformations in the backed plymaterial 10 (e.g., wrinkles), this path is typically calculated tocoincide with a “natural path” based upon any contours in the tool 34.As the tape laying head 18 is controlled along the path across the tool34, the compaction roller 24 is caused to exert sufficient pressure soas to adhere the ply material 12 to the tool 34. As the tape laying head18 moves along the path, the backed ply material 10 is drawn out of thetape laying head 18 and consolidated on to the tool 34. In this regard,composite layups typically include multiple layers of ply material.Thus, in subsequent applications of the ply material 12, backed plymaterial 10 is dispensed upon previously applied ply material.

At step 54, the placement of the backed ply material 10 on the tool 34is evaluated. For example, a sensor or an operator may sense therelative position of the backed ply material 10 and a previouslypositioned backed ply material 10 and determine if the distance betweenthese plies is within a predetermined tolerance. If the distance betweenthese plies is not within the predetermined tolerance, an error may begenerated at step 56. If the distance between these plies is within thepredetermined tolerance, it is determined if the supply is sufficient atstep 58. In addition, in some embodiments of the disclosure, the backing14 is removed from the backed ply material 10 following placementevaluation. However, the backing 14 need not be removed prior to step58, but rather, the backing 14 may be removed at essentially any timeprior to placement of a subsequent ply upon the backed ply material 10.Furthermore, it is an advantage of embodiments of the disclosure thatthe backing 14 is recyclable. That is, the backing 14 may be collectedand submitted to a recycling facility where the PET constituent of thebacking 14 may be processed to generate products. For the purpose ofthis disclosure, the term, “recycling” is defined as the act ofcollecting the backing 14 for submission to a recycling facility and/orthe reprocessing of the backing 14.

At step 58, it is determined whether the supply of ply material issufficient. For example, if it determined that the supply spool 20contains ply material then, it is determined that sufficient plymaterial remains. If it is determined that then is an insufficientamount of remaining ply material, the supply spool 20 is replaced atstep 60. If it is determined that a sufficient amount of ply materialremains then, it is determined if the end of the path has been reachedat step 62.

At step 60 the supply spool 20 is replaced. For example, a spent supplyspool 20 is removed from the tape laying head 18 and a substantiallyfull supply spool 20 may be disposed within the tape laying head 18.Following replacement of the supply spool 20, a splice is optionallyformed at step 64. For example, if the supply of ply material isexhausted during the placement of a ply, the ply material 12 for theuncompleted path may be removed or, optionally, spliced to the plymaterial 12 from the new supply spool 20. If the splice is performed,the particular steps performed are dependent upon the ply materialutilized and the product being laid up. However, in general, thetrailing edge of the uncompleted ply and the starting edge of the newply material are cut to match. These cut edges are abutted and qualitycontrol procedure procedures are performed.

An advantage of embodiments of the disclosure over conventional backedply material is that, due to the relative thinness of the backing 12, arelatively greater amount of ply material fits on the spool and thus,fewer spool change and tape splicing operations need be performed.

At step 62, it is determined if the end of the path has been reached.If, based on the series of computer readable instruction, it isdetermined the tape laying head 18 has not advanced to the end of thepath, additional backed ply material 10 is dispensed at step 52. If, itis determined the tape laying head 18 has advanced to the end of thepath, the backed ply material 10 is cut at step 66.

At step 66, the end of the ply material 12 may be cut based upon theseries of computer readable instruction, the orientation of a previouslypositioned ply material 12, and/or the location of a previouslypositioned ply material 12.

At step 68, it is determined if the placement of the ply material 12 onthe tool 34 has been completed. For example, if all of the computerreadable instructions have been completed, it may be determined that theplacement of plies for the composite product has been completed and theCTLM 38 may idle until another series of computer readable instructionsis initiated. If is determined the placement of plies 12 for thecomposite product is not completed, an additional ply material 12placement may proceed at step 48.

Following the method 44, the composite product may be cured in anysuitable manner. In the aerospace industry, thermoset resins aregenerally utilized to pre-impregnate ply material. These thermosetresins are typically cured by being held at an elevated temperature fora predetermined amount of time. Times and temperatures may be selecteddepending on the resin used, the size and thickness of the compositeproduct, and the like.

Although an example of the tape laying head 18 is shown utilizing thebacked ply material 10 for composite products in the airline industry,the backed ply material 10 can also be used in other industries thatconstruct composite product. These industries include, but are notlimited to, automobile, marine, spacecraft, building, and consumerproducts.

FIG. 5 is a flow diagram of steps performed in a method 70 to generatethe backed ply material 10 according to FIG. 1. As shown in FIG. 5, themethod 70 is initiated in response to a press or other such device beingturned on. Prior to initiation of the method 70 a variety of tasks maybe performed. These tasks include, in no particular order: secure asupply of the ply material 12 within the press; secure a supply of thebacking 14 within the press; mount an essentially empty spool downstreamof the press; and the like.

At step 72 the ply material 12 and the backing 14 are introduced intothe press.

At step 74 sufficient force and/or heat are applied to the ply material12 and the backing 14 so as to cause the ply material 12 and the backing14 to adhere.

At step 76 the backed ply material 12 is taken up by the spool. Inaddition, in response to a sufficient amount of backed ply material 12being placed upon the spool, the backed ply material 12 is cut, theessentially full spool is removed, and a substantially empty spool isoptionally put in its place.

The many features and advantages of the disclosure are apparent from thedetailed specification, and thus, it is intended by the appended claimsto cover all such features and advantages of the disclosure which fallwithin the true spirit and scope of the disclosure. Further, sincenumerous modifications and variations will readily occur to thoseskilled in the art, it is not desired to limit the disclosure to theexact construction and operation illustrated and described, andaccordingly, all suitable modifications and equivalents may be resortedto, falling within the scope of the disclosure.

1. A layered material, comprising: a ply material; and a backing filmdisposed upon the ply material, the backing film comprising a polyesterfilm.
 2. The layered material of claim 1, wherein the backing filmfurther comprises: a release coating to facilitate removal of thebacking film from the ply material.
 3. The layered material of claim 2,wherein the release coating comprises silicone.
 4. The layered materialof claim 1, wherein the backing film is about 0.001 to about 0.004inches thick.
 5. The layered material of claim 4, wherein the backingfilm is about 0.001 to about 0.002 inches thick.
 6. The layered materialof claim 1, wherein the backing film is substantially transparent. 7.The layered material of claim 1, wherein the backing film comprisespolyethylene terephthalate.
 8. The layered material of claim 1, whereinthe backing film is heat stabilized.
 9. The layered material of claim 1,wherein the ply material comprises graphite fibers.
 10. The layeredmaterial of claim 1, wherein the ply material comprises a metal foil.11. The layered material of claim 10, wherein the metal foil is epoxyresin coated metal foil.
 12. The layered material of claim 10, whereinthe metal foil comprises a titanium foil.
 13. The layered material ofclaim 1, wherein the ply material comprises titanium graphite composite.14. The layered material of claim 1, wherein the backing film isrecyclable.
 15. An apparatus for generating a backed ply material, theapparatus comprising: means for disposing a polyester film upon a plymaterial; and means for generating a roll of the backed ply material bywrapping the backed ply material about a spool.
 16. The apparatus ofclaim 15, wherein the polyester film is substantially transparent. 17.An apparatus for generating a composite layup, comprising: a means fortacking a ply material having a polyester backing film to a tool; ameans for disposing the ply material upon the tool along a path; andmeans for removing the polyester backing film.
 18. The apparatus ofclaim 17, further comprising: means for cutting the ply material inresponse to disposing the ply material at an end of the path. 19.apparatus of claim 17, wherein the polyester backing film is atransparent polyester backing film, the apparatus further comprising:means for generating an interface between two courses of the plymaterial by disposing the ply material upon the tool adjacent to apreviously applied course of the ply material; and means for viewing theinterface through the transparent polyester backing film to verify thatthe interface is within a predetermined tolerance.